drivers: espi: Obtain correct Rx lenght during OOB transaction.
drivers: espi: Obtain correct Rx lenght during OOB transaction.

MEC15xx eSPI OOB RX length register holds received message length
and receive buffer length, need to extract rcvd msg length.

Signed-off-by: Jose Alberto Meza <93346bcba00086196ffe58e37d7adff1143c3f07@intel.com>

Vudentz/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,nashif/zephyr,finikorg/zephyr,Vudentz/zephyr,nashif/zephyr,nashif/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,Vudentz/zephyr,finikorg/zephyr,finikorg/zephyr,Vudentz/zephyr,Vudentz/zephyr,finikorg/zephyr,Vudentz/zephyr